Null likelihood

See merge request Monash/peyote!11

Moritz Huebner: Implemented default value checks and cleaned up the code a bit. Should not have implications to any outside functions. Also cleaned up some obsolete code

Moritz Huebner: Implemented default value checks and cleaned up the code a bit. Should not have implications to any outside functions

start to split the likelihood into bitesize chunks

See merge request Monash/peyote!10

Source reimplementation

See merge request Monash/peyote!13

# Conflicts:
#   peyote/detector.py
#   peyote/likelihood.py
#   peyote/sampler.py
#   tutorials/BasicTutorial.py
#   tutorials/Injection.py

Moritz Huebner: Changed some more to align with current origin/master version, code now does the same thing as origin/master